If you pick up on an allusion to the great Fellini film in the title of Alfonso Cuaron’s latest drama, it seems both coincidental and not-so. “Roma” is the name of a neighborhood in Mexico City, where the filmmaker grew up. But as with Fellini, Cuaro´n also uses the medium as a place for memories to play in impressionistic fashion. The director of “Gravity” and “Children of Men,” gave his great cinematographer Emmanuel Lubezki the day off, as it were, taking up the camera himself to lens the lush and mesmerizing black-and-white scenes. He glances back with an unsentimental eye to the story of four children, growing up in spirited, even chaotic, middle-class surroundings, with adults whose actions they don’t always understand.